| 摘要 |
<p>The invention relates to an electrical key switch comprising
a printed circuit board with multiple switch contacts and a reference trace that are normally electrically isolated from each other, and
a metal snap dome disposed above the printed circuit board, and having an outer edge in electrical contact with a reference trace, the dome having an elevated central region forming a downwardly facing cavity defined at its edge by a ridge disposed above the switch contacts, such that when the snap dome is actuated the ridge
about the central region engages the printed circuit board in an annular contact zone
across the switch contacts, making electrical contact between the snap dome and the switch contacts to electrically connect the switch element with the multiple switch contacts.</p> |
